Balanced flap converging/diverging nozzle

ABSTRACT

A nozzle having four sets of flaps is formed on the exhaust end of a turbojet engine. One set of main flaps is pivotally located downstream of an exhaust opening with a second set of balance flaps pivotally connected between said main flaps and the rear end of the engine. A third set of diverging flaps are pivotally mounted to the main flaps and extend downstream thereof with the downstream end of said diverging flaps being pivotally connected at their rearward end to a fourth set of external flaps which are pivotally mounted at their forward end to the outer housing of the engine by a lost-motion connection. The nozzle actuating system is connected to a plurality of levers on the main flaps by a unison ring which pivots the main flaps about their pivot means to obtain the desired nozzle opening. All of the flaps move in unison with the main flaps.

United States Patent 1 Swavely et al.

[ BALANCED FLAP CONVERGlNG/DIVERGING NOZZLE [75] Inventors: Craig E.Swavely; Richard E.

Teagle, both of North Palm Beach Fla.

[73] Assignee: United Aircraft Corporation, East Hartford, Conn 22Filed: Nov. 24, 1972 [21] Appl. No.: 309,567

Related U.S. Application Data [63] Continuation of Ser. No. 209,665,Dec. 20, 1971,

[45] Feb. 19, 1974 Primary Examiner-M. Henson Wood, Jr. AssistantExaminer-Michael Y. Mar Attorney, Agent, or FirmJack N. McCarthy 57ABSTRACT A nozzle having four sets of flaps is formed on the exhaust endof a turbojet engine. One set of main flaps is pivotally locateddownstream of an exhaust opening with a second set of balance flapspivotally connected between said main flaps and the rear end of theengine. A third set of diverging flaps are pivotally mounted to the mainflaps and extend downstream thereof with the downstream end of saiddiverging flaps being pivotally connected at their rearward end to afourth set of external flaps which are pivotally mounted at theirforward end to the outer housing of the engine by a lost-motionconnection. The nozzle actuating system is connected to a plurality oflevers on the main flaps by a unison ring which pivots the main flapsabout their pivot means to obtain the desired nozzle opening. ATl of theflaps move in unison with the main flaps.

11 Claims, 3 Drawing Figures BALANCED FLAP CONVERGING/DIVERGING NOZZLEThis is a continuation, of application Ser. No. 209,665 filed Dec. 20,l97l now abandoned.

The invention disclosed herein was made in the course of or under acontract with the Department of the Air Force.

BACKGROUND OF THE INVENTION This invention relates to variable areanozzles for turbojet engines and while many nozzles are in the priorart, none appear to provide the cooperating movement between divergingand converging flaps along with a balance flap and external flap such asset forth herein. Several prior art nozzle patents are identified in thespecification.

SUMMARY OF THE INVENTION A primary object of the present invention is toprovide a balanced flap convergent/divergent nozzle system having acontiguous variable divergent section.

In accordance with the present invention, a long flap system is providedhaving low external drag, high internal performance, and without theneed for high actuation forces.

A stable nozzle system is set forth that can provide internal geometryvariation for complete integration with the airframe for subsonic andsupersonic flight conditions. This nozzle is capable of attaining thecorrect area ratios and divergence angles for high internal performanceand the external geometry has a minimum of projected area for drag toact upon.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view illustrating theapplication of the invention to a turbojet engine.

FIG. 2 is an enlarged sectional schematic view taken through the nozzleand the rear portion of the engine showing the maximum area and minimumarea position of the flaps of the nozzle.

FIG. 3 is an enlarged sectional schematic view of a modification of thenozzle shown in FIG. 2.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, the engine2 shown includes the conventional compressor section 4, the burnersection 6, turbine section 8, and exhaust duct and nozzle section 10. InFIG. 2, the inner case 14 is shown fixed to the outer housing structure12 by a conical shaped connecting member 16. This member is attached tothe outer housing by bolts 18 and extends forwardly to a point where itis connected to the inner casing by bolts 20, forming the section of acone. An inner liner 22 is positioned around and fixedly spaced from theinner side of inner case 14.

A plurality of main flaps 30 are mounted for pivotal movement at therear end of the outer housing structure 12. These flaps are eachpivotally mounted on a bracket member 32 which extends inwardly from theend of the structure 12. An actuating arm 34 extends outwardly from eachflap and movement of the arm actuates the attached main flap 30 aboutits pivotal mounting. Each flap 30 is pivotally mounted at a desiredbalance point. In one nozzle design, this location was madeapproximately one-third of the distance from 39 extends from each of thecylinder and piston units 1 40 and is attached to the unison ring 36.The unison ring 36 is centered within and slides on track members 37.Each actuating rod 39 extends through an opening 41 in the connectingmember 16. A nozzle actuator 42 connects one side of the cylinder andpiston unit to an actuating pressure while opening the opposite side todrain thereby movably positioning the main flaps 30. An arrangement ofthis type is shown in U. S. Pat. No. 2,815,643.

A plurality of balance flaps 50 extend forwardly of the main flaps 30.Each flap 50 has its rearward end pivotally connected to the forward endof a main flap 30 while its forward end has cylindrical means 51 thereonwhich is mounted for axial movement in a I track means 53. Each trackmeans 53 is formed between a rearward extension of the inner case 14 anda rearward extending flange 15 on the connecting member 16. While asimple cylinder and track means has been shown, any type of devicepermitting axial movement along with a change in angular position of thebalance flap 50 can be used.

A plurality of divergent flaps 60 extend rearwardly of the main flaps30. Each flap 60 has its forward end pivotally connected to the rearwardend of a main flap 30 while its rearward end is pivotally connected tothe rear end of an external flap 70. Each external flap has its forwardend pivotally mounted at the rear end of the housing structure 12, justrearwardly of the bracket members 32. Each of these pivotal connectionscan include a lost-motion movement.

Each of the annular set of flaps, the balance flaps 50,

the main flaps 30, the divergent flaps 60, and the external flaps 70,can have seal means positioned along adjacent side edges of cooperatingflaps to prevent an excessive amount of leakage therebetween. Seal meansare shown in U. S. Pat. No. 2,972,226; U. S. Pat. No. 3,004,385; U. S.Pat. No. 2,697,907; and U. S. Pat. No. 2,910,828.

In operation, it can be seen that when the nozzle actuator 42 directs anactuating pressure to the forward side of the cylinder and piston unit40, the actuating rod 39 will place the unison ring 36 in its rearwardposition (as shown in solid in FIG. 2) with the flaps positioned so asto form the minimum throat portion at the hinge location between flaps30 and 60. When the nozzle actuator 42 directs an actuating pressure tothe rearward side of the cylinder and piston unit 40, the actuating rod39 will be moved forwardly placing the unison ring 36 in a more forwardposition with the flaps positioned differently. In FIG. 2, the phantomlines show the flaps 50, 30, and 60 in a position where the flaps 50 and30 form a long converging surface while the flap 60 continues to be thediverging portion.

Referring to FIG. 3, a plurality of main flaps 30A are mounted forpivotal movement at the rear end of the outer housing structure 12A.These flaps are each pivotally mounted on a bracket member 32A whichextends inwardly from the end of the structure 12A. An

actuating arm 34A extends from the flap 30A in the same manner as inFIG. 2 with the actuating mechanism also being the same. In FIG. 3, eachbalance flap 50A is pivotally mounted at its front end to the rear ofthe inner case 14A and has a cam surface 22 at the rear end which rideson a cam follower 24 positioned on the forward end of its cooperatingflap 30A. The flaps 30A, 60A, and 70A are each connected in the samemanner as the corresponding flaps in FIG. 2. However, flap 70A has itsforward end pivotally mounted on the housing structure 12A at a pointforwardly of the bracket member 32A. The nozzleshown in FIG. 3 permitsthe formation of a different configuration than that of FIG. 2, withoutvarying from the spirit of the invention.

In operation, it can be seen that when the nozzle actuator 42 directs anactuating pressure to the forward side of the cylinder and piston unit40, the flaps will be positioned so as to form the minimum throatportion at the hinge location between flaps 30A and 60A. As before, whenthe nozzle actuator 42 directs an actuating pressure to the rearwardside of a cylinder and piston unit 40, the valve flaps will bepositioned differently with the unison rings 36 in a more forwardposition. In

FIG. 3, thephantom lines show the flaps 50A forming the convergingportion with the flaps 30A and 60A forming a long diverging surface. Itis noted that the minimum throat area has now moved upstream to thehinged location between the flaps 50A and 30A. Further, approximatelythe same shallow divergence angle is maintained in both positions shownof the nozzle in FIG. 2 thereby providing high performance at bothsubsonic and supersonic pressure ratios.

Stop means can be located in the cylinder and piston unit 40 or betweenthe bracket members 32 and arms 34 to predetermine the range of movementof the main flaps 30 and 30A, and therefore the remaining associatedflaps, to arrive at the desired limit positions of the flaps.

An actuating system for a nozzle such as shown in this application, isdisclosed-in co-pending application Ser. No. 209,664 Filed Dec. 20,1971, now U.S. Pat. No. 3,730,436 for SYNCHRONIZED EXHAUST NOZZLEACTUATING SYSTEM to William M. Madden et;al. Further, an exit areaschedule selector system for a nozzle such as disclosed herein isdisclosed in copending application Ser. No. 209,803, Filed Dec. 20, 197l for EXIT AREA SCHEDULE SELECTOR SYS- TEM by Kenneth E. Harmon. A sealmeans for a nozzle such as disclosed herein is set forth in co -pendingapplication Ser. No. 2l0,0l7, Filed Dec. 20, 1971, for SEAL CENTERINGAND RETENTION MEANS by Connie W. McMath.

We claim: a

1. In combination with jet engine fixed structure, an exhaust nozzlemounted on said fixed structure, said nozzle comprising acircumferential row of first main flaps pivotally mounted on said fixedstructure for controlling the flow area therethrough, second balanceflaps located between the forward edge of said first main flaps and apoint on said fixed structure forwardly of the forward edge of saidfirst main flaps, third divergentflaps, fourth external flaps, saidthird divergent flaps having their forward ends pivotally mounted to therearward ends of said first main flaps, said fourth external flapshaving their forward ends pivotally mounted to said fixed structureradially outwardly from the pivotal mounting of the first main flaps,the rear ends of said third divergent flaps and said fourth externalflaps being pivotally connected together, and an actuating means forvariably positioning said first main flaps.

2. In combination with jet engine fixed structure, an exhaust nozzlemounted on said fixed structure, said nozzle comprising acircumferential row of first main flaps, means pivotally mounting saidfirst main flaps on said fixed structure for controlling the flow areatherethrough, second balance flaps being positioned between the forwardedge of said first main flaps and a point on said fixed structureforwardly of the forward edge of said first main flaps, third divergentflaps, said third divergent flaps having their forward ends pivotallymounted to the rearward ends of said first main flaps, first flapconnecting means for connecting each third divergent flap rearwardly ofits forward end to fixed structure radially outwardly from the pivotalmounting of the first main flaps, said first flap connecting meanshaving its forward end pivotally mounted to said fixed structureradially outwardly from the pivotal mounting of the first main flaps,said first flap connecting means having its rear end pivotally mountedto a third divergent flap rearwardly of its forward end, and anactuating means for variably positioning said first main flaps.

3. A combination as set forth in claim 2 wherein said first flapconnecting means comprises external flaps.

4. A combination as set forth in claim 2 wherein said engine fixedstructure includes an exhaust duct located forwardly of said exhaustnozzle, each main flap is pivotally mounted at a point downstream ofsaid exhaust duct and substantially in axial alignment therewith.

5. A combination as set forth in claim 4 wherein the forward end of saidsecond balance flaps are mounted around the rear end of the exhaustduct.

6. A combination as set forth in claim 2 wherein each main flap ispivotally mounted at a point one-third of its distance from its forwardend.

7. A combination as set forth in claim 2 wherein the nozzle throat canvary between the location where the first main flaps and second balanceflaps meet and the location where the first main flaps and thirddivergent flaps meet.

8. A combination as set forth in claim 2 wherein said engine fixedstructure includes an outer duct forming an external nacelle, said firstflap connecting means having their forward ends pivotally mounted to therear end of said nacelle.

.9. A combination as set forth in claim 8 wherein said first main flapsare mounted on brackets fixed to the inner side of said externalnacelle.

10. A combination as set forth in claim 9 wherein said first flapconnecting means has its forward end mounted forwardly of the pivotalmounting of said first main flaps, said first flap connecting meansengaging said outer casing along "a portion of their length when thenozzle throat is at its'minumum diameter.

11. A combinationv as set forth in claim 5 wherein a mounting means isprovided for the forward end of the second balance flaps around the rearend of the exhaust duct, said mounting means permitting the balanceflaps to move with the first main flaps while providing a balancingaction due to the forces acting on the balance flaps.

1. In combination with jet engine fixed structure, an exhaust nozzlemounted on said fixed structure, said nozzle comprising acircumferential row of first main flaps pivotally mounted on said fixedstructure for controlling the flow area therethrough, second balanceflaps located between the forward edge of said first main flaps and apoint on said fixed structure forwardly of the forward edge of saidfirst main flaps, third divergent flaps, fourth external flaps, saidthird divergent flaps having their forward ends pivotally mounted to therearward ends of said first main flaps, said fourth external flapshaving their forward ends pivotally mounted to said fixed structureradially outwardly from the pivotal mounting of the first main flaps,the rear ends of said third divergent flaps and said fourth externalflaps being pivotally connected together, and an actuating means forvariably positioning said first main flaps.
 2. In combination with jetengine fixed structure, an exhaust nozzle mounted on said fixedstructure, said nozzle comprising a circumferential row of first mainflaps, means pivotally mounting said first main flaps on said fixedstructure for controlling the flow area therethrough, second balanceflaps being positioned between the forward edge of said first main flapsand a point on said fixed structure forwardly Of the forward edge ofsaid first main flaps, third divergent flaps, said third divergent flapshaving their forward ends pivotally mounted to the rearward ends of saidfirst main flaps, first flap connecting means for connecting each thirddivergent flap rearwardly of its forward end to fixed structure radiallyoutwardly from the pivotal mounting of the first main flaps, said firstflap connecting means having its forward end pivotally mounted to saidfixed structure radially outwardly from the pivotal mounting of thefirst main flaps, said first flap connecting means having its rear endpivotally mounted to a third divergent flap rearwardly of its forwardend, and an actuating means for variably positioning said first mainflaps.
 3. A combination as set forth in claim 2 wherein said first flapconnecting means comprises external flaps.
 4. A combination as set forthin claim 2 wherein said engine fixed structure includes an exhaust ductlocated forwardly of said exhaust nozzle, each main flap is pivotallymounted at a point downstream of said exhaust duct and substantially inaxial alignment therewith.
 5. A combination as set forth in claim 4wherein the forward end of said second balance flaps are mounted aroundthe rear end of the exhaust duct.
 6. A combination as set forth in claim2 wherein each main flap is pivotally mounted at a point one-third ofits distance from its forward end.
 7. A combination as set forth inclaim 2 wherein the nozzle throat can vary between the location wherethe first main flaps and second balance flaps meet and the locationwhere the first main flaps and third divergent flaps meet.
 8. Acombination as set forth in claim 2 wherein said engine fixed structureincludes an outer duct forming an external nacelle, said first flapconnecting means having their forward ends pivotally mounted to the rearend of said nacelle.
 9. A combination as set forth in claim 8 whereinsaid first main flaps are mounted on brackets fixed to the inner side ofsaid external nacelle.
 10. A combination as set forth in claim 9 whereinsaid first flap connecting means has its forward end mounted forwardlyof the pivotal mounting of said first main flaps, said first flapconnecting means engaging said outer casing along a portion of theirlength when the nozzle throat is at its minimum diameter.
 11. Acombination as set forth in claim 5 wherein a mounting means is providedfor the forward end of the second balance flaps around the rear end ofthe exhaust duct, said mounting means permitting the balance flaps tomove with the first main flaps while providing a balancing action due tothe forces acting on the balance flaps.